Docs: add English language support (#170)

* feat: support lang entry build

* feat: vant support lang switch

* move lang iframe-router to utils & fix router link bug

* add en-US config && add some translation

* chang async. to async_ (support superman cdn)

* add layout translation

* change nav style

* upgrade zan-doc

* fix: doc config

* upgrade zan-doc && remove useless code

* fix changelog generate path

yarn.lock

@@ -2973,6 +2973,14 @@ fs-extra@^3.0.1:
     jsonfile "^3.0.0"
     universalify "^0.1.0"
 
+fs-extra@^4.0.2:
+  version "4.0.2"
+  resolved "https://registry.yarnpkg.com/fs-extra/-/fs-extra-4.0.2.tgz#f91704c53d1b461f893452b0c307d9997647ab6b"
+  dependencies:
+    graceful-fs "^4.1.2"
+    jsonfile "^4.0.0"
+    universalify "^0.1.0"
+
 fs-extra@~1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/fs-extra/-/fs-extra-1.0.0.tgz#cd3ce5f7e7cb6145883fcae3191e9877f8587950"
@@ -4144,6 +4152,12 @@ jsonfile@^3.0.0:
   optionalDependencies:
     graceful-fs "^4.1.6"
 
+jsonfile@^4.0.0:
+  version "4.0.0"
+  resolved "https://registry.yarnpkg.com/jsonfile/-/jsonfile-4.0.0.tgz#8771aae0799b64076b76640fca058f9c10e33ecb"
+  optionalDependencies:
+    graceful-fs "^4.1.6"
+
 jsonify@~0.0.0:
   version "0.0.0"
   resolved "https://registry.yarnpkg.com/jsonify/-/jsonify-0.0.0.tgz#2c74b6ee41d93ca51b7b5aaee8f503631d252a73"
@@ -7899,12 +7913,13 @@ yeast@0.1.2:
   version "0.1.2"
   resolved "https://registry.yarnpkg.com/yeast/-/yeast-0.1.2.tgz#008e06d8094320c372dbc2f8ed76a0ca6c8ac419"
 
-zan-doc@0.2.17:
-  version "0.2.17"
-  resolved "https://registry.yarnpkg.com/zan-doc/-/zan-doc-0.2.17.tgz#bea711d254d89121b52b47792aec5127fe66fedf"
+zan-doc@0.3.1:
+  version "0.3.1"
+  resolved "https://registry.yarnpkg.com/zan-doc/-/zan-doc-0.3.1.tgz#f421a90eeb8e399e4257d52f671bffd14efbd28e"
   dependencies:
     cheerio "0.22.0"
     decamelize "^1.2.0"
+    fs-extra "^4.0.2"
     markdown-it "^8.3.2"
     markdown-it-container "^2.0.0"
     node-watch "^0.5.5"